1. Field of the Invention
The present invention relates to a combination lock, and more particularly to a cylinder type combination lock in which the combination of numbers or the like can freely be set or changed to any other combination by the user.
2. Description of the Prior Art
Combination locks of the type having means for setting or changing the combination have been known. For instance U.S. Pat. Nos. 3,720,082 to Irving Feinberg et al and 3,766,758 to Henry Heine et al disclose a combination padlock which is capable of being set or changed to any combination of the user's choice. The change of the combination of these padlocks is made by turning dials to the preset combination to open the lock and pull out its shackle, turning the shackle a predetermined degree, pushing in the shackle at the turned position, and then turning the shackle in the opposite direction by a predetermined degree while holding the shackle in the depressed state to release the teeth of sleeves from grooves of the dial, whereby a sleeve-dial relationship may be changed to any desired new combination.
On the other hand, various cylinder type combination locks have hitherto been developed and sold, but within the knowledge of the inventor, there has been proposed no such type combination lock which can easily be set or changed to a combination selected by the user. A specific combination of the conventional cylinder type locks is set by the manufacturer and such locks are sold with a tag attached which shows information on the preset combination for opening the lock. If the user wishes to change the preset combination, he must use a specific tool to release an O-ring which maintains an outermost dial on a core of the lock body, change the relative position of the dials, and fix the O-ring again. Not only is the operation troublesome, but also the variety of possible combinations is limited.